The invention relates to a passenger car body structure having B-pillar reinforcements formed as hollow steel profiles which each have an upper attachment portion for attachment to a roof region and a lower attachment portion for attachment to a floor assembly or a side sill.
The invention further relates to a B-pillar reinforcement or a central pillar reinforcement for a passenger car motor vehicle body or passenger car body structure.
Motor vehicle bodies of passenger cars should be stable and ensure optimum protection for the occupants. With regard, inter alia, to side crash effects, the body structures of modern passenger car motor vehicle bodies are equipped in the side region with what are referred to as pillar reinforcements. In order to reinforce vehicle bodies or body structures in the region of their B-pillars or central pillars, various measures are known from the prior art.
A measure which is widespread in the prior art is the use of hot-formed or press-hardened shaped sheet metal parts, as described, for example, in DE 697 07 066 T2 and DE 10 2005 038 488 A1.
Another measure known from the prior art is the use of hollow profiles, as described, for example, in DE 10 2010 036 450 A1, DE 10 2008 024 274 A1 and DE 600 06 010 T2.
The object on which the invention is based is to provide an improved passenger car body structure of the type stated at the outset which can, in particular, also be produced simply and cost-effectively.
This and other objects are achieved by a body structure, as well as a tubular B-pillar reinforcement, according to embodiments of the invention.
The passenger car body structure according to the invention has B-pillar or central pillar reinforcements which are formed as hollow steel profiles and which are each designed with an upper attachment portion for attachment to the roof region of the body structure and a lower attachment portion for attachment to the floor assembly or a side sill of the body structure, with the result that these B-pillar reinforcements extend over the entire body height at their installation sites on the right and the left body side. According to the invention, provision is now made for these B-pillar reinforcements to be formed as one-piece tubes (or as tubular hollow profiles) of a high-strength steel material, wherein these tubes have a curved course with a constant radius of curvature or arc radius between their lower attachment portions and their upper attachment portions.
With particular preference, the tubes are formed over their entire axial course with a constant radius of curvature and thus have a curved course of constant radius. A tube is generally understood to mean an elongate hollow body which has, in particular, a single cross-sectionally closed cavity. A wide variety of cross-sectional shapes is possible, with round cross sections, in particular oval or circular cross sections, being preferred (so-called round tubes which can have a diameter of, for example, 30 mm to 70 mm). However, it is also possible to provide non-round or polygonal or more complex cross-sectional shapes, which can also have, for example, at least one concave portion. With particular preference, provision is made for the tubes to be formed over their longitudinal extent with uniform cross sections or with a constant cross section. A high-strength steel material is understood to mean a steel material which has an (ultimate) tensile strength of at least 1200 MPa and preferably of at least 1400 MPa.
An advantage of the invention can be seen in the fact that tubes which are formed from a high-strength steel material and have a curved course which is of constant radius or uniform can be produced in a comparatively favorable manner. (A preferred production method is explained in further detail hereinbelow.) A further advantage can be seen in the fact that identical tubes can be used for the right and the left body side. Furthermore, the tubes provided for example with a certain length can be tailored to different vehicle types by shortening.
Safety belt, door lock and door hinge fastenings and/or the like can be welded directly to the curved tubes. The stable tubes can thus at the same time also serve for the attachment of the relevant components and the associated introduction of force into the body structure.
The tubes can be incorporated into the body structure by way of upper and lower retaining elements, with it being possible for the tubes to be connected at their upper and lower attachment portions to these retaining elements in an integrally bonded manner (for example by welding or brazing) and/or in a form-fitting manner (for example, by use of correspondingly formed receptacles on the retaining elements). The retaining elements have connecting portions by which they can be fastened to the roof region or to the floor assembly or the side sills. The fastening can be achieved, for example, by welding, brazing, adhesive bonding, riveting and/or screwing. The retaining elements are preferably formed from metal and can be produced, for example, as cast parts, welded parts or formed parts. However, the retaining elements can also be formed from composite materials, for example CRP or GRP, in particular with metallic inlays. The retaining elements are preferably formed in such a way that they are pressure- or compression-loaded in the event of a side crash.
The body structure can be what is referred to as a lightweight structure which has numerous aluminum and/or fiber composite components. At least the roof region or the longitudinal roof members, the floor assembly and/or the side sills are preferably formed from a fiber composite material, in particular CRP or GRP. Particularly in this case, provision is made for the retaining elements to be adhesively bonded to these components formed from fiber composite material. Alternatively, a screwed connection and/or riveted connection can also be provided, for example.
The B-pillar or central pillar reinforcement according to the invention is characterized, analogously to the preceding explanations, in that it is formed as a one-piece tube of a high-strength steel material, wherein this tube has a curved course with a constant radius of curvature between its lower attachment portion or its lower end and its upper attachment portion or its upper end.
The tube is preferably a roll-profiled and laser-seam-welded tube. Roll-profiling is a continuous forming process in which a tube string is successively formed (endless manufacture) in a roll-profiling plant from a fed-in sheet metal strip (which is typically unwound from a coil) in a plurality of forming steps using rotating forming tools (these are pairs of rolls as a rule). The forming operation generally takes place cold and without active influencing of the structure. The edges of the sheet metal which abut as a result of the forming operation are laser-welded (or, where appropriate, even only laser-brazed) to one another with the formation of a longitudinal laser seam. Laser welding (or, where appropriate, laser brazing) preferably also takes place within the roll-profiling plant. Even the production of the curved shape can also take place within the roll-profiling plant. The tube string continuously produced in this way merely still requires to be cut to length on exiting the roll-profiling plant. The tubes produced piecewise have final geometries, that is to say further forming steps are not provided.
An advantage of roll-profiling can be seen in the fact that a high-strength sheet steel material (for example with at least 1200 MPa and preferably with at least 1400 MPa) can be already used as starting material. The high-strength sheet steel material has, for example, a homogeneous sheet thickness of 2 mm to 4 mm. (In principle, sheet metal strips having a non-homogeneous sheet thickness can also be used.) While maintaining the sheet thickness, the tube serving as pillar or central pillar reinforcement can thus have a substantially homogeneous wall thickness of 2 mm to 4 mm. Considerable energy, environmental and cost advantages are obtained to some extent by comparison with hot-forming or press-hardening. Furthermore, the roll-profiled tubes can have a better structure quality and/or surface quality.
The B-pillar reinforcement according to the invention can have welded-on or brazed-on safety belt, door lock and door hinge fastenings or the like. Furthermore, the B-pillar reinforcement can be connected at its upper end to an upper retaining element and at its lower end to a lower retaining element (for incorporation into a passenger car body structure). The B-pillar reinforcement according to the invention can also have a coating, for example a cathodic electrodeposition coating, or at least a corrosion protection coating, for example a zinc coating (galvanization) or aluminum coating. The coating preferably also covers any safety belt, door lock and/or door hinge fastenings. Provision is particularly preferably made for the coating or corrosion protection coating to have already been applied to the starting material (sheet steel material) used for roll-profiling. A correspondingly formed B-pillar reinforcement can be provided as a prefabricated part and incorporated or inserted into a body structure.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.